Dengue virus (DENV) represents an emerging/re-emerging infectious disease that causes significant human morbidity and mortality. It is estimated that there are 25 to 100 million cases of DENV infection each year and 2.5 billion people are at risk. Children and infants in endemic countries account for the majority of the 25,000 DENV-associated deaths that occur annually. There is currently no commercial vaccine available. We have developed an innovative vaccine platform that has shown in vivo efficacy against lethal flavivirus infection in two independent models (West Nile virus and Yellow Fever virus) and in this application we will expand on this foundation to develop and produce a new tetravalent vaccine against DENV. The critical obstacle faced by current approaches to live attenuated DENV vaccine development is viral interference, a phenomenon in which the host preferentially mounts an immune response to one or two (but not all) of the four DENV serotypes, leaving the vaccinated subject either unprotected or at potentially increased risk for severe disease if exposed to the wrong DENV serotype. To resolve this problem, our approach utilizes previously attenuated DENV vaccine strains (shown to be safe in human subjects) followed by inactivation with our proprietary hydrogen peroxide (H2O2)-based vaccine technology to prepare highly immunogenic formulations with the potential to elicit a balanced immune response to all four DENV serotypes. This vaccine project encompasses many of the key product development goals listed in RFA-AI-11-014 including, lead vaccine candidate optimization; evaluation of safety, toxicity, and immunogenicity; evaluation of efficacy in appropriate challenge models; evaluation of stability at optimal and elevated storage temperatures; and cGMP manufacturing of vaccine material suitable for completing all applicable IND-enabling preclinical studies. The successful completion of these objectives will result in cGMP-grade vaccine material suitable for future initiation of a Phase I clinical trial, a crucial milestone in the advancement of a human vaccine for this important NIAID Category A Priority Pathogen.